1. Field of the Invention
This invention relates, in machine tools such as a drilling exclusive-use machine, transfer machine, a multiple spindle drill head, a drilling machine and the like, to a device for attaching a tool such as a drill, a reamer or the like to a spindle thereof.
2. Description of the Prior Art
Drill chucks are well-known as such a device. A drill chuck can firmly attach a tool such as a drill to the spindle of the machine tool. The tool secured to the spindle by the drill chuck is rotated as the spindle rotates to machine work. As is well known, however, where drill chucks are used, it takes time to install and remove the tool.
The following device is known as a device with which one can save the time to attach and detach the tool and attach the tool to the spindle simply and speedily. Namely, the spindle is formed to have a hollow portion. In the hollow portion, a collet is provided and a drawbar is connected to the rear side of the collet. In attaching the tool, the base portion of the tool is inserted into the hollow portion from the opening end of the spindle. The base portion of the tool is firmly caught by the collet when the drawbar is pulled from behind the collet. However, with such device, it is very troublesome for an operator to go behind the spindle each time and pull the drawbar there. When the spindle is vertically disposed, it is additionally troublesome that the operator must rise to a high place in order to pull the drawbar.
In order to eliminate these troublesome points, a device as shown in FIGS. 22 and 23 has been proposed with which one can attach and detach the tool by an operation only at one side of the spindle. In the device shown in these figures, an installing and removing member 82 is adapted to be removable from a spindle 81. A tool 83 is attached to the installing and removing member 82. A connecting member 85 is mounted externally of the installing and removing member 82. A ball holder 86 mounted on a spindle 81 holds steel balls 87. An operating cylinder 88 provided on the outer preipheral side of the ball holder 86 is movable in an axial direction. In the state shown in FIG. 22, a locking surface 90 formed on the operating cylinder 88 is provided to prevent levitation of the steel ball 87 fitted in an engaging recess 89 of the connecting member 85. Thus, the installing and removing member 82 is not slipped out of the spindle 81. On the other hand, when the operating cylinder 88 is moved in a direction as indicated by arrow 91 as shown in FIG. 23, the steel ball 87 is freely levitated. Thus, the installing and removing member 82 together with the connecting member 85 may be taken out in a direction as indicated by arrow 92. Work for attaching the thus taken out installing and removing member 82 to the spindle 81 again may be easily accomplished in the state wherein the operating cylinder 88 is moved as shown in FIG. 23.
However, in the above-described device, since the steel ball is merely fitted in the engaging recess 89, the installing and removing member 82 can be moved axially, though slightly, with respect to the spindle 81. Because of this, where the tool 83 is rotated by the spindle 81 to machine work, the tool 83 is finely vibrated axially by a force applied by the work to the tool 83. Such fine vibration lowers the accuracy of finishing relative to the work and deteriorates finishing of the work.